signals: collect_signal: simplify the "still_pending" logic
[linux-2.6/mini2440.git] / net / netfilter / xt_u32.c
blob627e0f336d54b45b84f9417b0757d3320acf86c2
1 /*
2 * xt_u32 - kernel module to match u32 packet content
4 * Original author: Don Cohen <don@isis.cs3-inc.com>
5 * (C) CC Computer Consultants GmbH, 2007
6 * Contact: <jengelh@computergmbh.de>
7 */
9 #include <linux/module.h>
10 #include <linux/moduleparam.h>
11 #include <linux/spinlock.h>
12 #include <linux/skbuff.h>
13 #include <linux/types.h>
14 #include <linux/netfilter/x_tables.h>
15 #include <linux/netfilter/xt_u32.h>
17 static bool u32_match_it(const struct xt_u32 *data,
18 const struct sk_buff *skb)
20 const struct xt_u32_test *ct;
21 unsigned int testind;
22 unsigned int nnums;
23 unsigned int nvals;
24 unsigned int i;
25 __be32 n;
26 u_int32_t pos;
27 u_int32_t val;
28 u_int32_t at;
31 * Small example: "0 >> 28 == 4 && 8 & 0xFF0000 >> 16 = 6, 17"
32 * (=IPv4 and (TCP or UDP)). Outer loop runs over the "&&" operands.
34 for (testind = 0; testind < data->ntests; ++testind) {
35 ct = &data->tests[testind];
36 at = 0;
37 pos = ct->location[0].number;
39 if (skb->len < 4 || pos > skb->len - 4)
40 return false;
42 if (skb_copy_bits(skb, pos, &n, sizeof(n)) < 0)
43 BUG();
44 val = ntohl(n);
45 nnums = ct->nnums;
47 /* Inner loop runs over "&", "<<", ">>" and "@" operands */
48 for (i = 1; i < nnums; ++i) {
49 u_int32_t number = ct->location[i].number;
50 switch (ct->location[i].nextop) {
51 case XT_U32_AND:
52 val &= number;
53 break;
54 case XT_U32_LEFTSH:
55 val <<= number;
56 break;
57 case XT_U32_RIGHTSH:
58 val >>= number;
59 break;
60 case XT_U32_AT:
61 if (at + val < at)
62 return false;
63 at += val;
64 pos = number;
65 if (at + 4 < at || skb->len < at + 4 ||
66 pos > skb->len - at - 4)
67 return false;
69 if (skb_copy_bits(skb, at + pos, &n,
70 sizeof(n)) < 0)
71 BUG();
72 val = ntohl(n);
73 break;
77 /* Run over the "," and ":" operands */
78 nvals = ct->nvalues;
79 for (i = 0; i < nvals; ++i)
80 if (ct->value[i].min <= val && val <= ct->value[i].max)
81 break;
83 if (i >= ct->nvalues)
84 return false;
87 return true;
90 static bool
91 u32_mt(const struct sk_buff *skb, const struct net_device *in,
92 const struct net_device *out, const struct xt_match *match,
93 const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop)
95 const struct xt_u32 *data = matchinfo;
96 bool ret;
98 ret = u32_match_it(data, skb);
99 return ret ^ data->invert;
102 static struct xt_match u32_mt_reg[] __read_mostly = {
104 .name = "u32",
105 .family = AF_INET,
106 .match = u32_mt,
107 .matchsize = sizeof(struct xt_u32),
108 .me = THIS_MODULE,
111 .name = "u32",
112 .family = AF_INET6,
113 .match = u32_mt,
114 .matchsize = sizeof(struct xt_u32),
115 .me = THIS_MODULE,
119 static int __init u32_mt_init(void)
121 return xt_register_matches(u32_mt_reg, ARRAY_SIZE(u32_mt_reg));
124 static void __exit u32_mt_exit(void)
126 xt_unregister_matches(u32_mt_reg, ARRAY_SIZE(u32_mt_reg));
129 module_init(u32_mt_init);
130 module_exit(u32_mt_exit);
131 MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
132 MODULE_DESCRIPTION("Xtables: arbitrary byte matching");
133 MODULE_LICENSE("GPL");
134 MODULE_ALIAS("ipt_u32");
135 MODULE_ALIAS("ip6t_u32");